The current methods for treatment of bifurcation lesions include V-stenting, simultaneous kissing stent technique, kissing balloon technique, stent deployment in a main branch followed by angioplasty of a side branch, Drug Eluting Stents (DESs) specially designed for the bifurcation lesions, T-stenting, crush technique, provisional stenting and the like. The current methods of treatment of bifurcation lesions involve use of medical devices specially designed for use in the bifurcation such as, Bare Metal Stents (BMSs), DESs, Drug Eluting Balloons (DEBs) and angioplasty balloons.
When the BMSs are used for treating the bifurcation lesions, generally, the BMSs are deployed only in the main branch. The side branch is subjected to angioplasty or is left unattended. Alternatively, the BMSs are deployed in both the main branch and the side branch. Deploying the BMSs in both the main branch and the side branch may lead to metal overload in the bifurcation. The metal overload may further result in inflammation and thrombus formation. Also, owing to the complicated structure of the bifurcation, the BMSs may not be appropriate for treating the bifurcation lesions. Therefore, use of DEBs and DESs has gained significance in treatment of the bifurcation lesions.
However, the currently used DEBs and DESs use polymer for loading the drugs on surfaces of the DEBs and the DESs. Owing to the use of polymers, the currently used DEBs and DESs are associated with phenomenon like an inflammation, restenosis, an acute thrombus formation, a sub-acute thrombus formation and a late thrombus formation. Furthermore, in case of the DESs, the amount of drug that is supplied to the lesions generally depends on a metal to artery ratio. The metal to artery ratio of the currently used DESs is 10% to 20%. Therefore, only 10% to 20% of a portion of the lesions is supplied with the drug. In addition, because of the complicated structure of the bifurcation, the metal to artery ratio in case of the bifurcation is generally less than the metal to artery ratio in a general non-bifurcated artery.
In some instances, where the DEBs are used for treating the bifurcation lesions, the time for which the DEBs are exposed to the target site ranges from 30 to 90 seconds. The DEBs have to deliver an effective amount of the drug within these 30 to 90 seconds. In order to deliver the effective amount of the drug within these 30 to 90 seconds, a high amount of the drug has to be loaded on the DEBs. Even after loading a high amount of the drug, the DEBs may not deliver the desired amount of the drug in a short time of 30 to 90 seconds. Further, currently used DEBs can be loaded only with certain highly lipophilic drugs such as, paclitaxel. Whereas, the DEBs that can be loaded with a wider range of drugs are not available in the art.
Additionally, in the currently used DEBs, a drug is coated on the surface of the balloon when the balloon is in a folded configuration. Therefore, a substantial portion of the DEB remains uncoated with the drug. When the DEB is inflated, the portion of the lesion that is exposed to the uncoated portion of the DEB is not supplied with the drug. Therefore, the currently used DEBs may not adequately cover the entire portion of the bifurcation lesions.
Further, the particle size of the drugs as well as the polymers that are coated on the DESs and the DEBs are larger than the size of tissue pores at a target site. Therefore, a substantial amount of drug remains unabsorbed. The unabsorbed drug may be washed away in blood stream and may produce side effects.
Therefore, there is a need in the art for an improved drug-delivering insertable medical device for treating the bifurcation lesions that is associated with reduced instances of restenosis, acute thrombus formation, sub-acute thrombus formation, and late thrombus formation. Further, there is need in the art for an improved drug-delivering insertable medical device that can deliver a desired amount of drug to the bifurcation lesions within 30 to 90 seconds with an optimum loading of the drug.